Cannot find variable taxRate

Question

class Goods {
     //instance variables
     String description;
     double price;
     //constructor
     Goods (String desc, double pri)
          description = desc;
          price = pri;
     public void display()
          System.out.println("item " + description + " price " + price);
class Food extends Goods
     double calories;
     Food (String desc, double pri, double cal)
          super(desc, pri);
          calories = cal;
     public void display()
          super.display();
          System.out.println("Calories " + calories);
interface Taxable
  final double taxRate = 0.06 ;
  double calculateTax() ;
class Toys extends Goods
     int minimumAge;
     Toys (String desc, double pri, int minAge)
          super(desc, pri);
          minimumAge = minAge;
     public void display()
          super.display();
          System.out.println("Minimum Age " + minimumAge);
     public double calculateTax()
    return price * taxRate ;
class Books extends Goods
     String author;
     Books (String desc, double pri, String auth)
          super(desc, pri);
          author = auth;
     public void display()
          System.out.println("Author " + author);
     public double calculateTax()
          return price * taxRate;
public class InterfaceExample
  public static void main ( String[] args )
    Goods[] inventory =  new Goods[10];
    inventory[0] = new Goods( "bubble bath", 1.40 );
    inventory[1] = new Food ( "ox tails", 4.45, 1500 );
    inventory[2] = new Books ( "Emma", 24.95, "Austin" );
    inventory[3] = new Toys  ( "Leggos", 54.45, 8 );
    inventory[0].display();
    inventory[1].display();
    inventory[2].display();
    inventory[3].display();
}on line 57 compile tells me that it cannot find the variable taxRate but i have defined it in the Taxable interface
final double taxRate = 0.06;

Answer 1

You did define that taxRate variable in an interface you never implemented. Make sure your interface is available by addingimplements Taxableto the classes Toys and Books.